Blurry fonts in Readium

My first test was an EPUB version of Petzold's "Code", from O'Reilly and Associates. The typeface/font just looks horrid in Readium; for comparison, I unpacked the HTML and CSS, and loaded them directly in the browser, and took screenshots of both - you can see them displayed over/under at http://dl.dropbox.com/u/1192274/readium-font-problem.png. The top image is from the browser directly loading the HTML, the bottom image of the EPUB as rendered by Readium.